Conventionally, there is known a plasma generation device that radiates an electromagnetic wave to a region in which gas is ionized. Such a plasma generation device can be used for decomposing and detoxifying various air pollutants such as VOC (volatile organic compounds).
The inventors have proposed a plasma generation device that simultaneously employs electric discharge and microwave radiation (Patent Documents 1 and 2). For example, the gas treatment device disclosed in Patent Document 2 generates a small-scale plasma by means of spark discharge and radiates microwave pulses to the plasma. The energy of the microwave pulses is supplied to the charged particles in the plasma, thereby enlarging and growing the plasma.